The subject matter disclosed herein relates to elevator systems. More specifically, the present disclosure relates to elevator systems equipped with electromagnetic brake systems.
The use of electromagnetic brake systems is increasing in popularity in elevator systems. In emergency stop operation of these devices, such as during power interruptions or faults in the elevator system safety chain, the engagement of the brakes may result in a harsh feeling for passengers in the elevator car due to the abrupt deceleration of the elevator car. This is especially true in a downward travelling elevator car, when the brake forces and gravitational forces are acting in the same direction. Code bodies worldwide have restricted the performance of the electromagnetic brakes to address potential risks to passengers in these conditions.
In conventional roped elevator systems, due to heavier cars and counterweights and larger drive machine inertia, the rate of deceleration was relatively low. In newer elevator systems, elevator cars are much lighter, overall system inertia is lower, and the many systems are driven by traction belts, all which contribute to higher rates of deceleration during an emergency stop event. Further, the high rate of deceleration may result in belt slippage, which is unacceptable to certain code authorities.